2.1.1005 Part 1 Section 18.17.7.236, NPV

a.   The standard states that arguments that are numbers, empty cells, logical values, or text representations of numbers are included; arguments that are error values or text that cannot be translated into numbers are ignored.

In Office, arguments that are numbers or text that can be translated into numbers are included. arguments that are empty cells, logical values, or text that cannot be translated into numbers are ignored.